Coccidia

If you've done a fecal test on your chickens (and if you haven't, you should!), you may have seen the word "coccidia" on your results. It's one of the most common findings in backyard flocks, and while it sounds scary, understanding what it is and how to manage it will help you keep your birds healthy.

What is Coccidia?

Coccidia are microscopic parasites (protozoa) that live in the intestinal tract of chickens. There are several species of Eimeria that affect chickens, and most birds are exposed to them at some point in their lives. In fact, a low level of coccidia is normal in many chickens. The parasites are spread through droppings: an infected bird sheds coccidia "oocysts" (think of them as eggs) in their poop, and other birds pick them up while pecking around.

The trouble starts when the parasite load gets too high. This can happen when birds are stressed, overcrowded, kept in damp conditions, or have weakened immune systems. Young birds and rescued chickens are particularly vulnerable.

Symptoms to Watch For

Coccidiosis (the disease caused by coccidia) can range from mild to severe. Here's what to look for: lethargy and decreased activity, loss of appetite, weight loss or failure to gain weight, ruffled or puffed-up feathers, pale comb and wattles, bloody or watery droppings, and hunched posture.

Not all infected birds show symptoms. Some chickens can carry a moderate coccidia load without apparent illness, while others (especially young, stressed, or immunocompromised birds) can become very sick. This is why fecal testing is so important: it tells you what's happening inside before symptoms become severe.

How to Diagnose Coccidia

One easy and reliable way to know if your chickens have coccidia (and how much) is through a fecal test. You can collect a fresh poop sample and send it to a lab for analysis. The lab will look at the sample under a microscope and count how many coccidia oocysts are present. (See our article on how to do a fecal test for step-by-step instructions.)

Results are reported as "oocysts per gram" (OPG) of feces. Here's how to interpret the numbers:

• Low (<500 OPG): generally not concerning in healthy adult chickens. Monitoring is usually sufficient and treatment is typically not needed.

• Moderate (500-5,000 OPG): often tolerated by healthy adults, but may signal early disease in young, stressed, or immunocompromised birds. Light treatment or close monitoring may be appropriate.

• High (>5,000 OPG): indicates a significant parasite load and usually warrants treatment, especially if symptoms are present.

'Context matters. A count of 2,000 OPG in a healthy adult chicken is very different from the same count in a stressed rescue who just arrived at your place. Always consider the bird's age, health status, and living conditions when interpreting results.

How to Treat Coccidia

Corid (amprolium) is a widely used anticoccidial medication for chickens and is commonly used to control coccidiosis. It works by interfering with the parasite's ability to use vitamin B1 (thiamine), which slows coccidia replication and allows the chicken's immune system to catch up. Corid is available as a liquid (9.6% solution) at most feed stores.

Here are the dosages for Corid 9.6% liquid, administered in drinking water. Treatment decisions should be based on the whole picture, not just the OPG number. Low counts in healthy adult chickens often don't require treatment. Moderate or high counts may warrant treatment depending on the bird's age, symptoms, stress level, and living conditions. Birds with clinical signs of coccidiosis should be treated more aggressively, regardless of their OPG count.

• Heavy treatment: 2 tsp per gallon for 5-7 days (1/2 tsp per quart, 0.6 ml per cup)

• Light treatment: 1 tsp per gallon for 5-7 days (1/4 tsp per quart, 0.3 ml per cup)

Important notes: Mix fresh Corid water daily. Remove all other water sources so birds only drink the medicated water. Because Corid affects thiamine absorption, don't give vitamin B supplements during treatment.

Preventing Coccidia Problems

Since coccidia thrive in moist environments and spread through droppings, good management is your best defense.

Environment: Keep litter dry and spot-clean frequently. Don't leave wet feed on the ground. Elevate waterers to reduce contamination, and make sure your runs have good drainage.

Age segregation: Keep chicks and juveniles separate from adults. Adult chickens are often immune reservoirs, carrying low levels of coccidia without symptoms. That's normal for them, but it can overwhelm young birds who haven't built immunity yet.

Monitoring: Do fecal tests on juveniles and new intakes, especially if their background is questionable. Weigh your birds when you can. Weight loss often precedes other symptoms, so catching it early gives you a head start on treatment.

Why We Added Light Treatment to Our Intake Protocol

At Clorofil, we've always done fecal tests on every chicken that comes through our doors during quarantine. Our protocol includes prophylactic delousing and deworming upon arrival, and then we'd wait for the fecal results to come back (usually about a week) before treating for coccidia if needed.

But after several rescues where birds arrived with significant coccidia loads, we realized we were losing valuable time. Chickens like Ziva and Mika, rescued from the meat industry, came in with quite high counts. By the time we got the results and started treatment, we had lost a week. That's a week longer in quarantine, a week longer before they could move to a more comfortable space or be adopted.

So we made a change: we now include prophylactic Corid light treatment as part of our standard intake protocol, right alongside delousing and deworming. The logic is the same as prophylactic deworming. Most chickens we rescue come from situations where coccidia exposure is likely, and starting treatment immediately helps reduce their parasite load from day one.

There's one exception: if a bird arrives severely dehydrated or in very poor condition, we stabilize them first before starting any treatment. A dehydrated bird needs plain water and supportive care before medicated water.

Since implementing this change, we've found that quarantine goes more smoothly for birds who do have coccidia. They're already partway through treatment by the time we get the fecal results back, which means shorter overall quarantine times and less stress for the birds.

You can read our full quarantine protocol here.

The Takeaway

Coccidia are a fact of life for most chicken caregivers, but they don't have to be a crisis. Regular fecal testing helps you catch problems early, and Corid is an effective, accessible treatment. If you're taking in any birds from unknown origin, consider whether a prophylactic light treatment might make sense for your situation.